Lipocalin 2 mediates appetite suppression during pancreatic cancer cachexia

Lipocalin 2 (LCN2) was recently identified as an endogenous ligand of the type 4 melanocortin receptor (MC4R), a critical regulator of appetite. However, it remains unknown if this molecule influences appetite during cancer cachexia, a devastating clinical entity characterized by decreased nutrition and progressive wasting. We demonstrate that LCN2 is robustly upregulated in murine models of pancreatic cancer, its expression is associated with reduced food consumption, and Lcn2 deletion is protective from cachexia-anorexia. Consistent with LCN2's proposed MC4R-dependent role in cancer-induced anorexia, pharmacologic MC4R antagonism mitigates cachexia-anorexia, while restoration of Lcn2 expression in the bone marrow is sufficient in restoring the anorexia feature of cachexia. Finally, we observe that LCN2 levels correlate with fat and lean mass wasting and is associated with increased mortality in patients with pancreatic cancer. Taken together, these findings implicate LCN2 as a pathologic mediator of appetite suppression during pancreatic cancer cachexia.

The TLR7/8 agonist R848 remodels tumor and host responses to promote survival in pancreatic cancer

A priority in cancer research is to innovate therapies that are not only effective against tumor progression but also address comorbidities such as cachexia that limit quality and quantity of life. We demonstrate that TLR7/8 agonist R848 induces anti-tumor responses and attenuates cachexia in murine models of pancreatic ductal adenocarcinoma (PDAC). In vivo, tumors from two of three cell lines were R848-sensitive, resulting in smaller tumor mass, increased immune complexity, increased CD8⁺ T-cell infiltration and activity, and decreased Treg frequency. R848-treated mice demonstrated improvements in behavioral and molecular cachexia manifestations, resulting in a near-doubling of survival duration. Knockout mouse studies revealed that stromal, not neoplastic, TLR7 is requisite for R848-mediated responses. In patient samples, we found Tlr7 is ubiquitously expressed in stroma across all stages of pancreatic neoplasia, but epithelial Tlr7 expression is relatively uncommon. These studies indicate immune-enhancing approaches including R848 may be useful in PDAC and cancer-associated cachexia.

In the treatment of pancreatic ductal adenocarcinoma (PDAC), comorbidities such as cachexia limit quality of life and survival. Here, the authors show TLR7/8 agonist R848 remodels host and tumour immune responses, promoting survival and attenuating cachexia in murine models of PDAC.

MyD88 signalling is critical in the development of pancreatic cancer cachexia

BACKGROUND

Up to 80% of pancreatic cancer patients suffer from cachexia, a devastating condition that exacerbates underlying disease, reduces quality of life, and increases treatment complications and mortality. Tumour-induced inflammation is linked to this multifactorial wasting syndrome, but mechanisms and effective treatments remain elusive. Myeloid differentiation factor (MyD88), a key component of the innate immune system, plays a pivotal role in directing the inflammatory response to various insults. In this study, we tested whether MyD88 signalling is essential in the development of pancreatic cancer cachexia using a robust mouse tumour model.

METHODS

Sex, age, and body weight-matched wide type (WT) and MyD88 knockout (MyD88 KO) mice were orthotopically or intraperitoneally implanted with a pancreatic tumour cell line from a syngeneic C57BL/6 KRAS^G12D/+ P53^R172H/+ Pdx-Cre (KPC) mouse. We observed the effects of MyD88 signalling during pancreatic ductal adenocarcinoma progression and the cachexia development through behavioural, histological, molecular, and survival aspects.

RESULTS

Blocking MyD88 signalling greatly ameliorated pancreatic ductal adenocarcinoma-associated anorexia and fatigue, attenuated lean mass loss, reduced muscle catabolism and atrophy, diminished systemic and central nervous system inflammation, and ultimately improved survival. Our data demonstrate that MyD88 signalling plays a critical role in mediating pancreatic cancer-induced inflammation that triggers cachexia development and therefore represents a promising therapeutic target.

CONCLUSIONS

MyD88-dependent inflammation is crucial in the pathophysiology of pancreatic cancer progression and contributes to high mortality. Our findings implicate the importance of innate immune signalling pathways in pancreatic cancer cachexia and a novel therapeutic target.

Activation of PP2A and Inhibition of mTOR Synergistically Reduce MYC Signaling and Decrease Tumor Growth in Pancreatic Ductal Adenocarcinoma

In cancer, kinases are often activated and phosphatases suppressed, leading to aberrant activation of signaling pathways driving cellular proliferation, survival, and therapeutic resistance. Although pancreatic ductal adenocarcinoma (PDA) has historically been refractory to kinase inhibition, therapeutic activation of phosphatases is emerging as a promising strategy to restore balance to these hyperactive signaling cascades. In this study, we hypothesized that phosphatase activation combined with kinase inhibition could deplete oncogenic survival signals to reduce tumor growth. We screened PDA cell lines for kinase inhibitors that could synergize with activation of protein phosphatase 2A (PP2A), a tumor suppressor phosphatase, and determined that activation of PP2A and inhibition of mTOR synergistically increase apoptosis and reduce oncogenic phenotypes in vitro and in vivo. This combination treatment resulted in suppression of AKT/mTOR signaling coupled with reduced expression of c-MYC, an oncoprotein implicated in tumor progression and therapeutic resistance. Forced expression of c-MYC or loss of PP2A B56α, the specific PP2A subunit shown to negatively regulate c-MYC, increased resistance to mTOR inhibition. Conversely, decreased c-MYC expression increased the sensitivity of PDA cells to mTOR inhibition. Together, these studies demonstrate that combined targeting of PP2A and mTOR suppresses proliferative signaling and induces cell death and implicates this combination as a promising therapeutic strategy for patients with PDA. SIGNIFICANCE: These findings present a combinatorial strategy targeting serine/threonine protein phosphatase PP2A and mTOR in PDA, a cancer for which there are currently no targeted therapeutic options.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/79/1/209/F1.large.jpg.

Abstract 3779: The TLR7/8 agonist R848 induces antitumor responses and attenuates cachexia in a murine model of pancreatic ductal adenocarcinoma

PURPOSE: With recent advances in immunotherapy, many novel cancer treatments are rapidly entering the clinical arena. However, immunotherapies may differ from traditional chemotherapies in their effects on cachexia and treatment-associated sickness. Cachexia is a common comorbidity of cancer that limits therapeutic options, decreases quality of life, and increases mortality risk. Many chemotherapy agents induce or worsen cachexia by independently causing anorexia, weight loss, muscle wasting, and fatigue. Acute systemic inflammation, an effect of many immunotherapies, results in sickness responses that are typically self-limited in healthy individuals. Whether immunotherapy-associated sickness is self-limited or chronic in the context of cancer, and how cachexia is impacted by immunotherapy, remains unknown.

METHODS: We recently found that the TLR7/8 agonist R848 reduces tumor size in mice implanted with epithelial cells from a syngeneic KRASG12D/+ P53R172H/+ Pdx-Cre (KPC) pancreatic tumor. To assess cachexia outcomes and R848-induced sickness, mice were orthotopically implanted with KPC cells or saline, and 2 days later were randomized to daily IP R848 (10µg) or vehicle until sacrifice (n=5-7/group/experiment, 3 experiments). Mice were tracked for weight, food intake, body composition, and locomotor activity (LMA), with end-stage analysis of tissue mass and gene expression.

RESULTS: Initially, KPC-bearing mice treated with R848 developed significant weight gain and ascites, but had a similar degree of anorexia and decreased LMA as vehicle-treated KPC-bearing mice. However, ongoing R848 resulted in subsequent tumor regression, decreased ascites, increased appetite, and increased LMA. At necropsy, KPC-bearing mice treated with R848 had a 50-70% reduction in tumor mass, histologically characterized by lymphocytic infiltrate and germinal centers. Furthermore, R848-treated KPC-bearing mice had improved total lean mass and heart mass; decreased expression of genes related to skeletal and cardiac muscle catabolism (Mafbx, Murf1, Foxo1, Bnip3, Gabarapl, Ctsl) and hepatic acute phase reactants (Orm1, Apcs); a trend toward decreased CNS inflammatory gene expression (Selp, Il1r1); and unchanged brown adipose tissue thermogenic gene expression (Ucp1). In sham-operated mice, R848 resulted in self-limited anorexia and weight loss, without muscle wasting or decreased LMA. Current work is underway to elucidate tumor intrinsic and tumor extrinsic mechanisms of R848 in this model.

SUMMARY: These studies show that R848 does not independently cause sustained sickness, and in a murine model of pancreatic cancer, can induce antitumor responses and improve cachexia outcomes. This represents a key difference from many cytotoxic chemotherapies and suggests immunotherapy approaches may be useful in the treatment of cachexia-associated malignancies.

Citation Format: Katherine A. Michaelis, Mason A. Norgard, Xinxia Zhu, Peter R. Levasseur, Katherine R. Pelz, Kevin G. Burfeind, Terry K. Morgan, Daniel L. Marks. The TLR7/8 agonist R848 induces antitumor responses and attenuates cachexia in a murine model of pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3779.